This application claims the priority of German Application No. 196 15 744.7, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an impact absorbing outer body structure of a motor vehicle, and more particularly to an outer body structure of a motor vehicle including an outer panel and means for the rapid displacement of at least part of the outer panel in response to an impact load. The invention also relates to a method of absorbing an impact load at an outer body structure of a motor vehicle, and a method of manufacturing an impact absorbing outer body structure of a motor vehicle.
A motor vehicle of the type generally described above is known from DE 28 14 107 A1. In order to provide improved protection for pedestrians in the event of an impact on the hood of a passenger vehicle, the hood can be raised rapidly out of its rest position into an impact position upon detection of an impact load. For the purpose of raising the hood approximately to the level of a cowl panel in front of a windshield of the passenger vehicle, an air-bag device is provided, which is triggered by appropriate signals of an impact sensor system. In order to permit upward displacement of the hood, the lock of the hood is released, and the air-bag device pivots the hood upwards, around its front hinge axis, by a certain distance.
A similar means for protecting pedestrians is provided in a motor vehicle according to DE 27 11 338 A1.
Japanese patent document JP 07156749 A discloses a motor vehicle having front, top body outer-panel regions provided with air-bag arrangements which, in the event of the motor vehicle colliding with a pedestrian, inflate and thus damp the impact of the pedestrian on the vehicle.
Japanese patent document JP 07125603 A discloses a similar means of protecting a pedestrian, a front region of the hood of the motor vehicle being provided with an opening from which an air bag can inflate in the event of pedestrian impact.
In Japanese patent document JP 07125604 A, the hood of a motor vehicle is covered by a soft sheet-like structure, similar to a netting, which can be stretched out in a matlike manner in the event of a collision with a pedestrian in order thus to cushion the impact of the pedestrian on the hood.
Japanese patent document JP 07125605 A discloses an air-bag arrangement on the hood of the motor vehicle which, in the inflated state, damps the impact of a pedestrian on the hood.
It is also known, from Japanese patent document JP 07125606 A, to provide a flap in the hood of the motor vehicle, an air-bag arrangement which can expand rapidly being provided beneath said flap. In the event of a collision of the motor vehicle, in particular, with a pedestrian, the air-bag arrangement is inflated such that it extends upward beyond the top of the hood and toward the windshield of the motor vehicle.
It is also known, from Japanese patent document JP 07125607 A, to provide a vertically displaceable cover in the hood of a motor vehicle. This cover is connected to an air-bag arrangement such that it is displaced vertically upward in the event of the air bag expanding. The air bag expands in the event of a collision between the motor vehicle and a pedestrian, as a result of which the pedestrian makes impact on the cover, which has been displaced vertically upwards, and this cover is deformed. The cover constitutes a component which is separate from the rest of the hood.
Japanese patent document JP 07125608 A discloses a motor vehicle having a hood provided with an opening for the expansion of an air-bag arrangement. When the air-bag arrangement is in the collapsed, rest state, this opening is closed by two push-open covers which are moved into their open position, in which the opening in the vehicle hood is exposed, in dependence on the air bag expanding.
A similar covering means for an air bag in the hood of a motor vehicle is known from Japanese patent document JP 07125609 A. In the case of this means for protecting a pedestrian, the opening in the hood is closed off by a pivotable flap which, for release of the air bag, is pivoted, towards the windshield, into its open end position.
Objects of the invention are to provide an impact absorbing outer body structure of a motor vehicle of the type generally described above which is relatively simple and compact, while providing improved impact protection for both pedestrians and other types of impact loads.
These and other objects have been achieved according to the present invention by providing an impact absorbing outer body structure of a motor vehicle, comprising: an outer body panel having at least one plastically deformable impact region; a supporting shell firmly connected to an inner side of the outer body panel such that a closed cavity is defined between the supporting shell and the impact region; and a high pressure charge which is dischargeable into the closed cavity in response to an impact load in order to deform the impact region of the outer body panel outwardly.
These and other objects have also been achieved according to the present invention by providing a method of absorbing an impact load at an outer body structure of a motor vehicle, comprising the steps of: providing an outer body panel having at least one plastically deformable impact region; connecting a supporting shell to an inner side of the outer body panel such that a closed cavity is defined between the supporting shell and the impact region; sensing an impact load; and pressurizing the closed cavity in response to an impact load such that the impact region of the outer body panel is deformed outwardly.
These and other objects have also been achieved according to the present invention by providing a method of manufacturing an impact absorbing outer body structure of a motor vehicle, comprising the steps of: forming an outer body panel having at least one plastically deformable impact region having a thickness less than a thickness of the rest of the outer body panel; forming a supporting shell having a thickness at least as great as the thickness of the rest of the outer body panel; connecting the supporting shell to an inner side of the outer body panel such that a closed cavity is defined between the supporting shell and the impact region; arranging an impact sensor system on the motor vehicle to sense an impact load; and arranging a high pressure discharge means in communication with the closed cavity and operatively connected to the impact sensor.
The present invention can be used, in particular, on hoods of motor vehicles, which are usually positioned relatively closely above a rigid drive unit, without the anchoring means of the hood having to be released. However, the solution according to the invention may also advantageously be used in vehicle side doors, in order for it to be possible for the impact energy of a side-impact load to be dissipated effectively in the side door. Upon detection of an impact load by a corresponding impact sensor system, the cavity between the supporting shell and the impact region of the outer panel is, in a simple manner, rapidly subjected to high pressure. The high pressure buckles the impact region of the outer panel buckles outward and curves the outer panel toward the person or object making impact thereon, resulting in a relatively large deformation distance between the impact region of the outer panel and the supporting shell for the dissipation of the impact energy. In this arrangement, the supporting shell need not necessarily be completely rigid. Even with the required space for the supporting shell beneath the outer panel, it is possible, in addition to the outer panel buckling, for the supporting shell to be deformed correspondingly in the opposite direction, towards the interior of the vehicle, with the result that both the is outer panel and the supporting shell are forced apart from one another by a certain distance.
In one preferred embodiment of the invention, the impact region of the outer panel has a wall thickness which is reduced in relation to the rest of the outer panel. This is a particularly simple configuration of the invention in order for the outer panel to be weakened effectively, and rendered sufficiently plastically deformable, in its impact region. Rupturing or breaking of the outer panel in the buckled state has to be avoided in order to prevent any additional injury hazards. Depending on material selection, however, it is also possible to weaken the outer panel in the impact region in another way. The outer panel may also be weakened, in particular, by dispensing with stiffening elements, such as stiffening beads, stiffening ribs or the like, in the impact region.
In a further configuration of the invention, the supporting shell is supported, towards the interior of the vehicle, on a functional unit, in particular a drive unit, which is fixed to the vehicle. This prevents the supporting shell from buckling too far inward due to excessive pressure loading, which could result in a reduction in the buckling of the impact region of the outer panel. It is precisely as a result of the impact region buckling outward to a sufficient extent, however, that desired early contact of the person or object with the outer panel, and thus with the body part, is achieved, this contact resulting in energy being absorbed at a relatively early stage, and thus in energy being dissipated to a certain extent before the person or object comes into contact with fixed block-type parts of the motor vehicle.
These and other objects, features and advantages of the present invention will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.